Recovery method and recovery system

Abstract

A recovery method according to the present disclosure is a recovery method for recovering the capacity of an electrode active material of an electricity storage device having an electrode on which an electrode mixture containing the electrode active material is formed and containing an electrolyte solution that is in contact with the electrode and that contains a metal ion as a carrier ion and an electrolyte solvent. The recovery method includes an electrode recovery step of immersing the electrode of the electricity storage device in a recovery agent to recover the capacity of the electrode active material while maintaining the state of the electrode, the recovery agent being a solution containing an aromatic hydrocarbon compound in a reduced state, a metal ion of the same type as the carrier ion, a recovery agent solvent of an ether compound different from the electrolyte solvent, and an electrolyte solution.

What is claimed is: 
     
         1 . A recovery method for recovering the capacity of an electrode active material of an electricity storage device having an electrode on which an electrode mixture containing the electrode active material is formed and containing an electrolyte solution that is in contact with the electrode and that contains a metal ion as a carrier ion and an electrolyte solvent, the method comprising:
 an electrode recovery step of immersing the electrode of the electricity storage device in a recovery agent to recover the capacity of the electrode active material while maintaining the state of the electrode, the recovery agent being a solution containing an aromatic hydrocarbon compound in a reduced state, a metal ion of the same type as the carrier ion, a recovery agent solvent of an ether compound different from the electrolyte solvent, and an electrolyte solvent used for the electrolyte solution.   
     
     
         2 . The recovery method according to  claim 1 , comprising:
 in addition to or instead of the electrode recovery step, a decomposition-recovery step of immersing the electrode of the electricity storage device in a decomposition-recovery agent to recover the capacity of the electrode active material while decomposing the electrode mixture, the decomposition-recovery agent being a solution containing an aromatic hydrocarbon compound in a reduced state, a metal ion of the same type as the carrier ion, and a recovery agent solvent of an ether compound different from the electrolyte solvent, and not containing an electrolyte solvent used for the electrolyte solution.   
     
     
         3 . The recovery method according to  claim 2 , comprising:
 a degradation acquiring step of acquiring a degree of degradation of an electrode of the electricity storage device,   wherein the electrode recovery step is performed on the electrode of the electricity storage device when the degree of degradation is within a predetermined acceptable range, and the decomposition-recovery step is performed on the electrode of the electricity storage device when the degree of degradation is outside the acceptable range.   
     
     
         4 . A recovery method for recovering the capacity of an electrode active material of an electricity storage device having an electrode on which an electrode mixture containing the electrode active material is formed and containing an electrolyte solution that is in contact with the electrode and that contains a metal ion as a carrier ion and an electrolyte solvent, the method comprising:
 a decomposition-recovery step of immersing the electrode of the electricity storage device in a decomposition-recovery agent to recover the capacity of the electrode active material while decomposing the electrode mixture, the decomposition-recovery agent being a solution containing an aromatic hydrocarbon compound in a reduced state, a metal ion of the same type as the carrier ion, and a recovery agent solvent of an ether compound different from the electrolyte solvent, and not containing an electrolyte solvent used for the electrolyte solution.   
     
     
         5 . The recovery method according to  claim 1 , wherein the recovery agent solvent contains at least one of tetrahydrofuran (THF), dimethyl ether (DME), diethyl ether (DEE), diglyme (G2), triglyme (G3), and tetraglyme (G4). 
     
     
         6 . The recovery method according to  claim 1 , wherein the electrolyte solvent is a carbonate compound. 
     
     
         7 . The recovery method according to  claim 1 , wherein the aromatic hydrocarbon compound is at least one of the compounds represented by the formula (1) and (2). 
       
         
           
           
               
               
           
         
         However, n is an integer of 1 or more and 4 or less, and m is an integer of 1 or more and 4 or less. 
         The aromatic ring may have a substituent or a heteroatom in its structure. 
       
     
     
         8 . The recovery method according to  claim 1 , wherein the aromatic hydrocarbon compound in the reduced state is in a concentration range of 0.1 to 3 mol/L. 
     
     
         9 . The recovery method according to  claim 1 , wherein the electrode active material is a lithium transition metal composite compound. 
     
     
         10 . A recovery system for recovering the capacity of an electrode active material of an electricity storage device having an electrode on which an electrode mixture containing the electrode active material is formed and containing an electrolyte solution that is in contact with the electrode and that contains a metal ion as a carrier ion and an electrolyte solvent, the system comprising:
 a recovery section for performing an electrode recovery process of immersing the electrode of the electricity storage device in a recovery agent to recover the capacity of the electrode active material while maintaining the state of the electrode, the recovery agent being a solution containing an aromatic hydrocarbon compound in a reduced state, a metal ion of the same type as the carrier ion, a recovery agent solvent of an ether compound different from the electrolyte solvent, and an electrolyte solvent used for the electrolyte solution.   
     
     
         11 . The recovery system according to  claim 10 , wherein in addition to or instead of the electrode recovery process, the recovery section performs a decomposition-recovery process of immersing the electrode of the electricity storage device in a decomposition-recovery agent to recover the capacity of the electrode active material while decomposing the electrode mixture, the decomposition-recovery agent being a solution containing an aromatic hydrocarbon compound in a reduced state, a metal ion of the same type as the carrier ion, and a recovery agent solvent of an ether compound different from the electrolyte solvent, and not containing an electrolyte solvent used for the electrolyte solution. 
     
     
         12 . The recovery system according to  claim 11 , comprising:
 a degradation acquisition section for acquiring a degree of degradation of the electrode of the electricity storage device,   the recovery section performs the electrode recovery process on the electrode of the electricity storage device when the degree of degradation is within a predetermined acceptable range, and performs the decomposition-recovery process on the electrode of the electricity storage device when the degree of degradation is outside the acceptable range.   
     
     
         13 . The recovery system according to  claim 10 , wherein the recovery agent solvent contains at least one of tetrahydrofuran (THF), dimethyl ether (DME), diethyl ether (DEE), diglyme (G2), triglyme (G3), and tetraglyme (G4). 
     
     
         14 . The recovery system according to  claim 10 , wherein the electrolyte solvent is a carbonate compound. 
     
     
         15 . The recovery system according to  claim 10 , wherein the aromatic hydrocarbon compound is at least one of the compounds represented by the formulae (1) and (2). 
       
         
           
           
               
               
           
         
         However, n is an integer of 1 or more and 4 or less, and m is an integer of 1 or more and 4 or less. 
         The aromatic ring may have a substituent or a heteroatom in its structure. 
       
     
     
         16 . The recovery system according to  claim 10 , wherein the aromatic hydrocarbon compound in the reduced state is in a concentration range of 0.1 to 3 mol/L. 
     
     
         17 . The recovery system according to  claim 10 , wherein the electrode active material is a lithium transition metal composite compound.